Calliostoma ligatum (Gould, 1849)

Common name(s): Blue top shell, costate top shell

Calliostoma ligatum captured at Sares Head and held in aquarium,
spring 2004. About 2 cm diameter.

(Photo by: Dave Cowles)

Description: A top shell with a pearly interior,
no nodes on columella, umbilicus closed, has tan, unbeaded spiral
ridges on a brown background (weathered parts of shell may appear blue),
whorls are slightly convex. Foot has an orange sole. Periostracum
is usually pinkish or reddish brown.

How to Distinguish from Similar Species: C.
variegatum (which is found mostly in deep water) has a shell mostly
tan, yellowish, or pale pink, and the spirals are beaded. C.
annulatum also has beaded spirals and the lower spiral on each
whorl is blue or purplish.

Geographical Range: Prince William SoundAlaska
to San Diego California. Uncommon in southern end of range.

Depth Range: Shallow intertidal to subtidal.
Abundant in low intertidal in Puget Sound (This is the only Calliostoma
that is abundant in the Sound).

Habitat: Common in eel grass and kelp.
Often found on brown algae such as Cystoseira and Macrocystis.

Biology/Natural History: Found in and around
kelp beds. Eats the kelp itself and adhering bryozoans, diatoms,
and detritus. May eat tunicate Cystodytes lobatus. Has
two muscular waves of contraction on foot while crawling, which move from
back to front of the foot and are out of phase with each other. Crawl
rapidly away from some seastars. Snail covers shell with mucus which
may aid in avoiding capture by seastars.

According to Baltzley et al., (2011),
many gastropods, including this species, have a special network of
pedal ganglia in their foot which assists in crawling. The two
main neurons involved produce pedal peptides which elicit an increase
in the rate of beating of cilia on the foot, resulting in crawling.